The need for machines to scrape or abrade floors to remove adhered waste material is well defined and, as is noted in U.S. Pat. No. 4,486,931 (Pichelman et al) granted on Dec. 11, 1984, various machines have been developed for this purpose. The particular example of Pichelman et al teaches the use of a large number of scarifying discs mounted vertically on a circular plate that rotates in a horizontal plane. The discs, with abrading peripheries that engage the floor, rotate in vertical planes. Noting earlier designs working on the scarifying disc principle, Pichelman et al also noted a tendency of such designs to "buck"-an undesirable feature because a floor can be gouged and damaged as a result. They address the problem, in part, by lowering the centre of gravity of rotating parts in their own design.
Other examples of floor scraping machines include the use of numerous wire blades organized in groups beneath a circular plate to provide a brush-like cutting action as the plate rotates: see U.S. Pat. No. 4,385,412 granted to Neufeldt on May 31, 1983. There is no comment on any tendency that the design may have to buck, but this, as well the effectiveness of the scraping action, may depend on the relative stiffness of the wire blades.
Machines calling for the use of a large number of rotary discs as in the case of Pichelman et al or a large number of wire blades as in the case of Neufeldt can be considered undesirable from a cost or maintenance point of view. In addition to purchase cost, the blade or scraping elements require more work to remove or install, and more work to service.
An example of a machine that could be used as a floor scraping machine even though it is not described as such may be found in U.S. Pat. No. 3,613,147 granted to Norfleet on Oct. 19, 1971. Norfleet describes a wall scraper tool in the nature of an accessory attachment for a hand-held power drill. The attachment includes four rigidly positioned scraper blades projecting below a circular plate. As the plate rotates, the blades perform a scraping action. Rollers are spaced around the periphery of the plate and, while their purpose is not clearly stated, it is likely that they are intended to limit gouging that might occur if the tool wobbles or bucks when in use.
In the design of prior art floor scraping machines, the action of cutting blades and the like is largely fixed and predetermined. There is no means for dynamic selfadjustment in response to changing operating conditions. This is believed to contribute to the tendency of such machines to gouge or become unstable. As well it limits the ability of the machine to accommodate uneven floor surfaces.
Accordingly, a primary object of the present invention is to provide a new and improved floor scraping machine that adjusts dynamically in response to changing operating conditions so as to lessen the possibility of damage to the floor or to the machine itself. (Machine damage can occur if, for example, a blade encounters an obstruction such as a nail or other hard object protruding from the floor).
A further object of the present invention is to provide a new and improved floor scraping machine that not only adjusts dynamically in response to changing floor conditions, but which may also be easily adjusted manually to preset cutting blades for pressure and depth of cut.